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Cougar Video
4.2 32X32 Video Matrix Card Continued:
Output
The output circuits on the 32X32 Video Matrix Card are responsible for
driving the output lines. The output circuits are comprised of an opera-
tional amplifier, a transistor, and their associated components. The opera-
tional amplifier is responsible for conditioning the output video signal and
driving the video output line through precision 75 ohm resistors. When the
BUSOFF signal, connected to the base of the transistor, is active high the
transistor will conduct collector to emitter and will shunt any unwanted
crosstalk noise to ground. An adjustment is provided in each output circuit
to adjust the output for unity gain.
Power
The power regulator circuits on the 32X32 Video Matrix Card are respon-
sible for producing all of the regulated operational voltages required by the
matrix card's electronic circuits. The power regulator circuits are also re-
sponsible for providing regulated power to the 16X16 Crosspoint Cards.
The heart of the power supply circuit on the video matrix card is a switch-
ing regulator (U117) which produces the +5.6V DC, -5.6V DC, and +5V
DC. Adjustment of the output of the regulator is provided by R479, a vari-
able resistor. CR7 provides a visual indication that power is being applied
to the input of the regulator circuits. Fuses F1 and F2 protect the power
regulator circuits from overload conditions and protect the circuit cards
from overload damage. The power circuits also contain a fan speed regu-
lator circuit which works in conjunction with fan regulator in the PS70V
Power Supply to control the speed of the associated chassis fans. As the
temperature of the matrix card's circuits increase the fan speed will in-
crease. Inversely as the matrix card's circuits decrease in temperature the
fan speed will slow down dependent upon the temperature of the associ-
ated PS70V Power Supply's circuits.
4.3 16X16 Crosspoint Card
The 16X16 Crosspoint Card contains a 16X16 matrix consisting of several
main circuits. This discussion will be broken down to the main circuits as
they are found on the schematics in Section 6 (Schematics).
11/97
P/N 81905903420
Functional
Section 4
4
F UNCTIONAL
DESC RIPTI ON
page 4.3
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